Stamicarbon B.v.

Jan Tijssen

Jozef L Van Der Loos

Wilhelmus G Duyzings

An improved process for the preparation of heat resistant copolymers of an alpha-methylstyrene and acrylonitrile by polymerization thereof in aqueous emulsion, and in the presence of a free-radical-supplying compound and a chain-transfer agent. The polymerization reaction is insufficiently cooled to remove all of the released reaction heat, and in combination therewith the polymerization is conducted at a temperature of the aqueous emulsion maintained at a level of at most 110.degree., while further maintaining the mean rate of temperature increase per hour, v, at a value of at most 60.degree. C. per hour, wherein v is determined by the formula: ##EQU1## in which: T.sub.m =maximum temperature of the aqueous emulsion (.degree.C.),

Process for the preparation of a copolymer comprising

The invention relates to a heat resistant polymer composition based on one or more graft copolymers of styrene and acrylonitrile on a rubber and a copolymer of .alpha.-methylstyrene and acrylonitrile. This composition comprises:

Polymer composition of .alpha.-methyl styrene/acrylonitrile copolymer

An improved process for the preparation of copolymers of .alpha.-methylstyrene and other co-monomers such as acrylonitrile styrene, methyl methacrylate and the like, wherein a substantially water-immiscible softener is employed, particularly prior to coagulation of the latex formed of the copolymer, whereby an improved product of higher bulk density and easier to employ in a subsequent processing is obtained.

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Geleen, Netherlands

Jan Tijssen